.backTop{
    display: block;
    width: 45px;
    height: 45px;
    border-radius: 50%;
    background-color:rgba(39,195,147,0.8);
    color: #fff;
    display: flex;
    justify-content: center;
    align-items: center;
}

.backtotop-hidden{
    display: none;
}

.backToTop .iconfont{
    font-size: 30px;
    color: #fff;
}